Prostate-specific antigen induces proliferation of peripheral blood lymphocytes and cytokine secretion in benign prostate hypertrophy patients

PURPOSE

The etiology of benign prostatic hypertrophy (BPH) is still obscure. Data supporting an interaction connecting prostate hyperplasia and immune dysregulation is accumulating lately. The aim of the study was to assess the cellular immune responses to PSA by measuring the in vitro potential of PSA to induce proliferation and cytokine secretion in peripheral blood lymphocytes (PBLs) of BPH patients.

MATERIALS AND METHODS

PBLs were extracted from fresh blood of 36 BPH patients and 11 age-matched controls. The PBLs were incubated with PSA. Proliferation of the cultured PBLs was determined by thymidine incorporation. Secretion of cytokines to the culture medium was measured either by biological assay (IL-2) or by ELISA (IL-4, IL-10, IFNgamma, TNFalpha).

RESULTS

Twelve of the 36 BPH patients responded to PSA, whereas none of the 11 controls responded (p = 0.04). The proliferative response of PBLs from BPH patients was significantly higher as compared to PBLs of controls (p = 0.03). The mean total prostate volume and the transition zone volume were 51% and 54% bigger, respectively, among the responders to PSA as compared to the nonresponders (p < 0.05), whereas the mean serum PSA level did not differ significantly. PBLs of BPH patients secreted significantly higher levels of TNFalpha, both spontaneously and in response to PSA, as compared to controls (p = 0.003).

CONCLUSIONS

These findings show that PSA is able to induce proliferation of PBLs in vitro in BPH patients. Moreover, the higher spontaneous and PSA-induced secretion of TNFalpha in BPH patients may reflect a role for this proinflammatory cytokine in vivo. Based on these observations, we suggest that autoimmune dysregulation might have a role in BPH.

Differing MHC class I requirements for induction and propagation of experimental systemic lupus erythematosus

Mice deficient in beta2-microglobulin expression are resistant to the induction of experimental systemic lupus erythematosus (SLE). The present studies were designed to identify the beta2-microglobulin-dependent cell surface molecule(s) that confers sensitivity to experimental SLE, and to determine its role in disease development. We report hat mice lacking the transporter associated with antigen presentation (TAP-/-) were also resistant to disease, whereas CD1-/- and CD8-/- mice were susceptible; susceptibility also did not correlate with neonatal Fc receptor or HEPH expression. These data indicate that disease susceptibility is determined by expression of MHC class I. Furthermore, by analyzing both adoptive transfer and radiation bone marrow chimeras, we demonstrate that MHC class I expression is necessary for propagation of disease, but not for induction of pathogenic cells.

DNA levels in immune complexes circulating in mice with induced systemic lupus erythematosus

The levels of DNA in IgG immune complexes, which appeared in the circulation of mice after the induction of systemic lupus erythematosus (SLE), were measured by an immunochemical quantitative assay using monoclonal anti-dsDNA antibodies. The amount of DNA in immune complexes was already high at 10-12 days following the injection of a human monoclonal anti-DNA antibody bearing the major idiotype designated 16/6 in complete Freund's adjuvant, i.e. long before the appearance of clinical manifestations. The injections of these antibodies in the alum-precipitated form did not induce the formation of DNA:anti-DNA complexes as well as SLE itself. The levels of DNA in circulating immune complexes were in general high throughout the whole experimental period (up to 7 months) decreasing gradually before the first clinical manifestations appeared and thereafter, when the disease was fully developed. Such a decrease could be explained by the retention of immune complexes in kidneys. The levels of DNA in immune complexes circulating in normal mice or in mice receiving injections of complete Freund's adjuvant was very low. Treatment of experimental SLE that affected the clinical manifestations prevented the formation of high levels of DNA containing immune complexes.

Immune activation in non-treated suicidal major depression

In the following study we have analyzed cytokine secretion of T-cells of suicidal and non-suicidal depressed patients and healthy controls. It was found that T-cells of suicidal depressed patients have Th1 characteristics, while T-cells of non-suicidal depressed patients have Th2 characteristics. Th1 environment is associated with most of autoimmune diseases. It is thus speculated that Th1 activation in suicidal depression may reflect a unique form of autoimmune suicide.

Altered peptide ligands act as partial agonists by inhibiting phospholipase C activity induced by myasthenogenic T cell epitopes

Myasthenia gravis (MG) is a T cell-regulated, antibody-mediated autoimmune disease. Two peptides representing sequences of the human acetylcholine receptor alpha-subunit, p195-212 and p259-271, previously were shown to stimulate the proliferation of peripheral blood lymphocytes of patients with MG and were found to be immunodominant T cell epitopes in SJL and BALB/c mice, respectively. Single amino acid-substituted analogs of p195-212 and p259-271, as well as a dual analog composed of the tandemly arranged two single analogs, were shown to inhibit, in vitro and in vivo, MG-associated autoimmune responses. Stimulation of T cells through the antigen-specific T cell receptor activates tyrosine kinases and phospholipase C (PLC). Therefore, in attempts to understand the mechanism of action of the analogs, we first examined whether the myasthenogenic peptides trigger tyrosine phosphorylation and activation of phospholipase C. For that purpose, we measured generation of inositol phosphates and tyrosine phosphorylation of PLC after stimulation of the p195-212- and p259-271-specific T cell lines with these myasthenogenic peptides. Both myasthenogenic peptides stimulated generation of inositol phosphates as well as tyrosine phosphorylation of PLC. However, the single and dual analogs, although inducing tyrosine phosphorylation of PLC, could not induce PLC activity. Furthermore, the single and dual analogs inhibited the induced PLC activity whereas they could not inhibit tyrosine phosphorylation of PLC that was caused by the myasthenogenic peptides. Thus, the altered peptides and the dual analog act as partial agonists. The down-regulation of PLC activity by the analogs may account for their capacity to inhibit in vitro MG-associated T cell responses.

Single amino acid analogs of a myasthenogenic peptide modulate specific T cell responses and prevent the induction of experimental autoimmune myasthenia gravis

Peptide p259-271 of the human acetylcholine receptor alpha-subunit, preferentially stimulates T cells of patients with myasthenia gravis (MG) and is an immunodominant epitope for T cells of BALB/c mice. A p259-271 specific T cell line of BALB/c origin was established and was shown to induce experimental MG in naive mice. Seven analogs of p259-271 were synthesized, and two of them were found to inhibit the p259-271 specific proliferative responses of the line and of p259-271 primed lymph node cells. Moreover, the most efficient inhibitor, analog 262Lys, prevented the MG related manifestations in mice inoculated with the line, and might be of potential value for the treatment of MG.

Anti-T-cell receptor therapy in murine experimental systemic lupus erythematosus

Experimental systemic lupus erythematosus (SLE), similar to that observed after immunization with the human anti-DNA mAb 16/6 Id+, could be induced in mice by injection of 16/6 Id specific T-cell lines. The above T-cell lines were exclusively CD4+ CD8- and the majority of cells expressed the Vbeta8 T-cell receptor (TCR) gene products. Furthermore, lymph node cells of mice immunized with the 16/6 Id were enriched with CD4+ Vbeta8+ T-cells. The TCR used by 16/6 Id-specific T-cells showed a limited homology in their CDR3 junctional regions. Nevertheless, mice injected with the anti-Vbeta8 mAb developed autoantibody titers that were not significantly different from those found in the non-treated, 16/6 Id-injected group.

Spontaneous autoimmune disease in (NZB x NZW)F1 mice is ameliorated by treatment with methimazole

(NZB x NZW)F1 mice spontaneously develop with age an autoimmune disease that resembles the human disease, systemic lupus erythematosus (SLE). The present study demonstrates that methimazole (MMI), an agent used in the treatment of autoimmune thyroid disease, is effective in mitigating the development of this SLE-like autoimmune disease in (NZB x NZW)F1 mice. MMI significantly reduces the incidence and severity of proteinuria and deposition of immune complexes in the kidney. Previous studies have demonstrated that development of an experimentally induced SLE, which was prevented by MMI treatment, depended on the expression of MHC class I molecules. We now report that class I levels on both T cells and B cells from old (NZB x NZW)F1 MHC class I are markedly elevated relative to those from young F1 mice. Furthermore, treatment of (NZB x NZW)F1 mice with MMI reduced MHC class I expression on their PBL concomitant with amelioration of disease, raising the possibility that class I molecules may play a role in the generation of spontaneous autoimmune disease in these mice.

Role of MHC class I molecules in autoimmune disease

The MHC class I molecules play a pivotal role in triggering cellular immune responses, binding and presenting intracellularly derived peptide antigens. Studies of MHC class I expression revealed a complex regulatory mechanism that integrates tissue-specific and hormonal modulation. Dynamic regulation occurs in the thyroid, in response to hormonal repression by TSH and stimulation by thyroid hormone. This dynamic cycle provides the basis for proposing the model that such regulation is important to maintain tolerance to self-antigens in tissues synthesizing large amounts of secretory proteins. Failure to appropriately regulate class I levels is predicted to result in autoimmunity. In support of this model, we found that class I-deficient mice are resistant to the experimentally induced autoimmune diseases, SLE, and blepharitis. Furthermore, pharmacological treatment with an agent that reduces class I expression also reduces the incidence and severity of both experimental and spontaneous autoimmune SLE.

Genetic analysis of experimentally induced lupus in mice

The DBA/2 and C57BL/6 mouse strains, as well as the BXD RI lines derived from these strains, were used to map the genes controlling experimentally induced systemic lupus erythematosus (SLE). SLE was induced using two immunologic approaches: (1) immunization with the human monoclonal anti-DNA antibody expressing the 16/6Id, to which the DBA/2 strain is susceptible (responder) and the C57BL/6 strain is resistant (nonresponder); and (2) induction of autoimmune GVHD in B6D2F1 hosts by inoculation of parental DBA/2 (induces SLE) or C57BL/6 (does not induce SLE) T cells. By both approaches the BXD RI lines could be divided into distinct DBA/2-like and C57BL/6-like categories. Concordance of SLE induced by both methods was observed for susceptibility and resistance in 13/15 BXD lines (P < 0.005). The results suggest that at least two non-H-2 genes control susceptibility and resistance to experimentally induced SLE, one mapping to chromosome 7 and the other mapping to chromosome 14.

T cell receptor expression and differential proliferative responses by T cells specific to a myasthenogenic peptide

Myasthenia gravis (MG) is a T-cell-regulated autoimmune disease in which a pathological autoantibody response is mounted against the nicotinic acetylcholine receptor of the neuromuscular junction. Our laboratory previously identified a T cell epitope, p195-212, derived from the human acetylcholine receptor alpha subunit, which triggered PBL to proliferate from about 70% of MG patients tested. p195-212 was also found to be an immunodominant T cell epitope in SJL mice and a cryptic epitope in C3H.SW mice. Inoculation of naive SJL mice with cells from a p195-212-specific syngeneic T cell line caused MG-related autoimmune manifestations in those mice. In these studies we analyzed TCR alpha and beta chain sequences used by T cell lines and clones from both high- and low-responder mouse strains in response to p195-212. T cell lines generated from either strain expressed single TCR V beta gene segments (V beta 17 in SJL mice and V beta 8 in C3H.SW mice). By deleting V beta 17-expressing T cells in p195-212-immunized SJL mice we established a T cell line that expressed the V beta 6 gene product, suggesting that SJL mice are not limited to using a single V beta gene segment in response to p195-212. In addition, we found that N- and/or C-terminal-truncated peptides of p195-212, presented under the same culture conditions to different clones bearing the same TCR alpha beta chain, could elicit very different proliferative responses from the clones. Thus, even within a constrained system, factors other than TCR sequence contribute to the differential stimulation of T cell responses.

Cytokine manipulation by methotrexate treatment in murine experimental systemic lupus erythematosus

OBJECTIVE

We reported beneficial effects of methotrexate (MTX) treatment on clinical variables in the murine model of experimental systemic lupus erythematosus (SLE). We now follow the kinetics of several cytokines that are involved in experimental SLE, to find out whether MTX treatment has an effect on cytokine production.

METHODS

SLE was induced in naive BALB/c female mice by injection of the human monoclonal anti-DNA antibody bearing the common idiotype, 16/6 Id. Six weeks after booster injection, when high levels of autoantibodies were observed, MTX treatment was started (2 mg/kg once a week) for 7 months. Cytokine production by macrophages or splenocytes from these mice was determined monthly by either ELISA or bioassays.

RESULTS

A significant increase in the production of tumor necrosis factor-alpha was determined as early as 2 weeks after injection. Interleukin 1 (IL-1) production increased gradually, starting one month after disease induction. These proinflammatory cytokines reached very high levels that were maintained through disease course. MTX treatment reduced production of these cytokines to normal levels throughout the experimental period. Increased levels of IL-2 and interferon-gamma (IFN-gamma), the Th1 type cytokines, were detected 2-4 months after disease induction. The secretion of the latter then dropped to levels lower than those observed in control mice. Treatment with MTX reversed levels of the cytokines to levels observed in healthy mice, IL-4 and IL-10, the Th2 type cytokines, predominated later in disease course, 5 months after immunization. Two to 3 months later production of IL-4 dropped to levels lower than those of control mice. IL-10 secretion remained higher than in controls throughout the experiment. The production of both IL-4 and IL-10 in MTX treated mice was also similar to that of control mice.

CONCLUSION

The restoration of the cytokine profile to normal levels observed in the MTX treated mice from the initial steps of disease induction suggests its beneficial effects in SLE might be mediated through modulation of cytokine production.

Reactivity of T cells from seronegative patients with myasthenia gravis to T cell epitopes of the human acetylcholine receptor

Seronegative (SN) patients with myasthenia gravis (MG) have clinical and electrophysiologic features similar to those of seropositive (SP) patients, and they respond to the same therapeutic measures. However, because SN patients lack detectable (by standard radioimmunoassays) serum antibodies to acetylcholine receptor (AChR), which are considered to have a crucial role in MG, the pathophysiologic basis for the disease is not clear. We therefore compared the ability of peripheral blood lymphocytes (PBL) of SN patients (11) and SP patients (39) to respond to myasthenogenic T cell epitopes of human AChR. We tested two aspects that relate to T-cell immunity: 1) T cell responses to myasthenogenic peptides by proliferation and IL-2 production, and 2) the ability of antigen-presenting cells to bind these T-cell epitopes. T cells of SN patients did not differ from those of SP patients in their ability to respond and to bind the two human AChR-derived myasthenogenic peptides. This supports the belief that most SN patients indeed suffer from an autoimmune disease directed against the AChR. The presence of T-cell immunity in the absence of antibodies may emphasize the importance of AChR-specific T cells in MG.

Effect of aging on cytokine production in normal and experimental systemic lupus erythematosus afflicted mice

The objective of the this study was to determine the cytokine profile of aging mice and to establish whether changes in cytokine production account for the fact that aging mice develop a milder disease than the young in response to induced experimental systemic lupus erythematosus (SLE). Cytokine secretion was evaluated in groups of BALB/c and C3H.SW mice at different ages between 2 and 24 months. The production of IL-2, IL-4, IL-10, IFN gamma and TNF alpha was determined in supernatants of ConA-stimulated splenocytes and that of IL-1 in the supernatants of LPS-stimulated peritoneal macrophages. A gradual age-related decline was observed in the production of IL-2 and IFN gamma, whereas the levels of IL-4, IL-10, IL-1 and TNF alpha progressively increased with aging, in unimmunized BALB/c and C3H.SW mice. Experimental SLE was induced in 2 and 10 month old C3H.SW mice by immunization with the monoclonal anti-DNA antibody bearing the 16/6 Id. The characteristic cytokine profile following immunization of 2 month old mice was early increased production of TNF alpha and IL-1, followed by a peak of Th1 type cytokines (IL-2, IFN gamma). At a later stage of the disease, a peak of Th2 type cytokines (IL-4, IL-10) was observed that was concomitant with low levels of Th1 cytokines. In contrast, in the 10 month old mice that were immunized with 16/6 Id only a mild increase in all the above cytokines was observed. We suggest that the lower autoantibody production and moderate clinical manifestations in aging mice with experimental SLE are causally related to the decreased production of pro-inflammatory cytokines at the initial stages of the disease followed by a lower production of both Th1 and Th2 type cytokines.

Modulation of murine systemic lupus erythematosus with peptides based on complementarity determining regions of a pathogenic anti-DNA monoclonal antibody

Experimental systemic lupus erythematosus (SLE) can be induced in naive mice by immunization with a murine monoclonal anti-DNA antibody (mAb), 5G12, that bears a major idiotype designated 16/6 Id. Strain-dependent differences were observed in the proliferative responses of lymph node cells of mice immunized with two peptides based on the sequences of the complementarity determining region (CDR) 1 and 3 of mAb 5G12. The capacity of the peptides to bind to major histocompatibility complex class II molecules correlated with the proliferative responses. Immunization of high responder strains with the CDR-based peptides led to production of autoantibodies and clinical manifestations characteristic to experimental SLE. The CDR-based peptides could prevent autoantibody production in neonatal mice that were immunized later either with the peptide or with the pathogenic autoantibody. Furthermore, the peptides inhibited specific proliferation of lymph node cells of mice immunized with the same peptide, with mAb 5G12 or with the human mAb anti-DNA, 16/6 Id. Thus, the CDR-based peptides are potential candidates for therapy of SLE.

A peptide composed of tandem analogs of two myasthenogenic T cell epitopes interferes with specific autoimmune responses

Myasthenia gravis (MG) is a T cell-regulated, antibody-mediated autoimmune disease. Two peptides representing sequences of the human acetylcholine receptor alpha-subunit, p195-212 and p259-271, were previously shown to stimulate peripheral blood lymphocytes of patients with MG and were found to be immunodominant T cell epitopes in SJL and BALB/c mice, respectively. Single amino acid substituted analogs of p195-212 (analog Ala-207) and p259-271 (analog Lys-262) were synthesized. We showed that analogs Ala-207 and Lys-262 inhibited, in vitro and in vivo, the proliferative responses of T cell lines specific to the relevant peptide and lymph node cells of mice immunized to p195-212 and p259-271, respectively. To inhibit T cell responses to both peptides (p195-212 and p259-271), we synthesized dual analogs composed of the tandemly arranged two single (Ala-207 and Lys-262) analogs (dual analog) either sequentially (Ala-207-Lys-262) or reciprocally (Lys-262-Ala-207). In the present study, we report that both dual analogs could bind to major histocompatibility complex class II molecules on antigen-presenting cells of SJL and BALB/c mice. Analog Lys-262-Ala-207, which bound more efficiently to major histocompatibility complex class II molecules, was found to inhibit the proliferative responses of both p195-212- and p259-271-specific T cell lines. Furthermore, the analog inhibited the in vivo priming of lymph node cells of both SJL and BALB/c mice when administered i.v., i.p., or per os. The dual analog Lys-262-Ala-207 could also immunomodulate myasthenogenic manifestations in mice with experimental autoimmune MG induced by inoculation of a pathogenic T cell line. Thus, a single peptide that is composed of analogs to two epitope specificities can be used to regulate T cell responses and disease associated with each epitope.

Kinetics of cytokine production in experimental systemic lupus erythematosus: involvement of T helper cell 1/T helper cell 2-type cytokines in disease

We followed cytokine production from induction through disease progression in a murine model of experimental systemic lupus erythematosus (SLE). SLE was induced by immunization with the human monoclonal anti-DNA Ab that bears the common Id designated 16/6 Id. BALB/c and C3H.SW mice that are susceptible to SLE induction and C57BL/6 mice that are resistant were immunized with the 16/6 Id. Cytokine production was tested periodically for 7 mo. Increased production of IL-2 and IFN-gamma, the Th1-type cytokines, was detected in BALB/c and C3H.SW mice 2 to 4 mo following immunization. IL-4 and IL-10, the Th2-type cytokines predominated later in disease course, and peaked 5 mo following disease induction. At this stage the Th1 type cytokines dropped to levels below those observed in controls. IL-4 production also dropped rapidly to very low levels, while IL-10 production decreased but remained above control levels. The ratio of IgG2a/IgG1 of DNA and 16/6 Id-specific Abs peaked at 2 mo following disease induction and decreased later, in concordance with the higher production of Th2-type cytokines. Thus, the development of experimental SLE in mice involves two stages: increased production of Th1-type, followed by increased induction of Th2-type cytokines. High levels of the proinflammatory cytokines, TNF-alpha and IL-1, were maintained throughout disease course. No significant changes were detected in the cytokine profile of C57BL/6 immunocytes following immunization with the 16/6 Id, supporting the possible role of the cytokine network in SLE.

Kinetics of cytokine production in experimental systemic lupus erythematosus: involvement of T helper cell 1/T helper cell 2-type cytokines in disease

We followed cytokine production from induction through disease progression in a murine model of experimental systemic lupus erythematosus (SLE). SLE was induced by immunization with the human monoclonal anti-DNA Ab that bears the common Id designated 16/6 Id. BALB/c and C3H.SW mice that are susceptible to SLE induction and C57BL/6 mice that are resistant were immunized with the 16/6 Id. Cytokine production was tested periodically for 7 mo. Increased production of IL-2 and IFN-gamma, the Th1-type cytokines, was detected in BALB/c and C3H.SW mice 2 to 4 mo following immunization. IL-4 and IL-10, the Th2-type cytokines predominated later in disease course, and peaked 5 mo following disease induction. At this stage the Th1 type cytokines dropped to levels below those observed in controls. IL-4 production also dropped rapidly to very low levels, while IL-10 production decreased but remained above control levels. The ratio of IgG2a/IgG1 of DNA and 16/6 Id-specific Abs peaked at 2 mo following disease induction and decreased later, in concordance with the higher production of Th2-type cytokines. Thus, the development of experimental SLE in mice involves two stages: increased production of Th1-type, followed by increased induction of Th2-type cytokines. High levels of the proinflammatory cytokines, TNF-alpha and IL-1, were maintained throughout disease course. No significant changes were detected in the cytokine profile of C57BL/6 immunocytes following immunization with the 16/6 Id, supporting the possible role of the cytokine network in SLE.

The beneficial effects of treatment with tamoxifen and anti-oestradiol antibody on experimental systemic lupus erythematosus are associated with cytokine modulations

In an attempt to elucidate the role of oestrogens in systemic lupus erythematosus (SLE) we investigated the effects of treatment with an oestrogen antagonist-tamoxifen and a monoclonal anti-oestradiol (anti-E2) antibody on mice in which experimental systemic lupus erythematosus (SLE) was induced by a human monoclonal anti-DNA antibody bearing the 16/6 idiotype (16/6 Id). Thus, groups of BALB/c female mice were immunized with the 16/6 Id and 3 weeks following the booster injection, when antibody titres were elevated in the injected mice, treatment protocols with anti-oestradiol or tamoxifen were initiated. Control groups that were not immunized with the 16/6 Id but were similarly treated with the above agents were included in the study. The treatment with the above agents had no effect on the total autoantibody titres; however, a decrease in the immunoglobulin G (IgG)2a/IgG1 ratio of the anti-DNA antibodies was determined in the 16/6 Id immunized and treated mice. Further both the anti-oestradiol and tamoxifen had beneficial effects on the clinical manifestations (white blood cell counts, levels of protein in the urine and immune complex deposits in the kidneys) of the 16/6 Id immunized and treated mice. We have previously observed a significant elevation in interleukin-1 (IL-1) and tumour necrosis factor-alpha (TNF-alpha) secretion in mice with experimental SLE and a reduction in IL-2, IL-4 and interferon-gamma (INF-gamma) levels as compared with the levels detected in healthy controls. Treatment with either the anti-oestradiol antibody or with tamoxifen restored the levels of all the above cytokines to the normal levels observed in the control mice. These findings suggest that cytokine modulation may be the basis for the therapeutic effects of both anti-oestrogens in experimental SLE.

Altered peptide ligands of a myasthenogenic epitope as modulators of specific T-cell responses

Myasthenia gravis (MG) is a T-cell regulated autoimmune disease. A peptide representing a sequence of the human acetylcholine receptor alpha-subunit (p195-212) was previously shown to stimulate proliferative responses of peripheral blood lymphocytes from MG patients and to be an immunodominant and myasthenogenic T-cell epitope in SJL mice. The authors generated a panel of analogues of p195-212 that contain single amino acid substitutions. Three of the analogues (203PHE, 204GLY and 207ALA) triggered low to no proliferative responses of a p195-212-specific T-cell line designated TCSJL195-212. Two of these analogues were able to stimulate the line to produce interleukin-2 (IL-2) and IL-4 (203PHE and 204GLY), whereas one analogue, 207ALA, did not stimulate the line to produce these cytokines. Binding assays revealed that the binding affinity of an altered peptide for a given major histocompatibility complex (MHC) molecule is not sufficient to determine whether it will be stimulatory or inhibitory to a native peptide-specific T-cell line. Two of the analogues, 204GLY and 207ALA, inhibited proliferative responses of cells of the TCSJL195-212 line when co-cultured with p195-212 and syngeneic antigen presenting cells (APC). The two inhibitory analogues were also able to inhibit proliferative responses of the TCSJL195-212 line when APC were pre-pulsed with p195-212, indicating that MHC blockade is not the only mechanism of action of these peptides. Moreover, both analogues inhibited the ability of p195-212 to prime lymph node cells for proliferative responses even when the analogues were administered in a soluble form. Thus the altered peptide ligands 207ALA and 204GLY can modulate T-cell responses both in vitro and in vivo and may have therapeutic potential for the treatment of MG.

Defective maternal-fetal interaction in a murine autoimmune model

Anti-cardiolipin antibodies (ACA) are associated with recurrent fetal loss, but their role in this pathological condition is unknown. We recently developed an experimental mouse model of the anti-phospholipid syndrome, in which immunization of female mice with a monoclonal anti-cardiolipin antibody resulted in substantial failure of pregnancy. We observed that pre-implantation embryos derived from ACA-injected mothers exhibited morphological abnormalities and failed to implant in vitro. In the present study, we designed embryo transfer experiments to determine whether defective embryonic development originated as a maternal defect, an embryonic defect or both. Embryos (3.5 day old), taken from ACA- and control-immunized mothers were transferred into either an ACA- or a control-treated uterine environment (day 2.5 pseudopregnant females). On day 14 of gestation the incidence of pregnancy, the average number of fetuses per female and fetal resorptions were assessed. The ACA-treated uterine environment was found to be non-supportive for the development and implantation of normal embryos. Moreover, embryos derived from ACA-immunized mothers, even after their removal from the ACA-environment and transfer to a normal uterus, remained deficient. These results demonstrate that both the maternal and the embryonic compartments were defective, as a result of previous exposure to the ACA.

MHC class II-mediated T cell response to DNA

Anti-DNA antibodies are elevated in several autoimmune diseases, including systemic lupus erythematosus. Yet, DNA was not shown to be presented by molecules of the major histocompatibility complex (MHC), nor was it reported to specifically stimulate T cells in vivo, although these steps are essential for antibody production. We now demonstrate DNA-specific T cell activation, which involves presentation of DNA by MHC class II molecules. T cells, isolated from lymph nodes of mice immunized with a murine monoclonal anti-anti-DNA antibody, proliferated in response to DNA. Moreover, presentation of DNA by murine antigen-presenting cells could be inhibited with an isotype-specific anti-Ia antibody, and with peptides restricted by the same H-2 haplotype, suggesting that it is MHC class II-mediated. These results indicate that DNA can play a direct role in the regulation of T cells and in autoimmune processes.

Variable regions of two murine antibodies that bind the SLE associated 16/6 idiotype

Experimental systemic lupus erythematosus can be induced in naive mice of different strains using a human monoclonal antibody bearing the 16/6 idiotype and a murine anti-16/6 Id monoclonal antibody designated 1A3-2. Herein we report the isolation of a second anti-16/6 Id antibody, 3F7-8, from BALB/c mice afflicted with experimental SLE. In contrast to the previously reported (1A3-2) anti-16/6 Id monoclonal antibody, mAb 3F7-8 does not induce experimental SLE upon immunization. The variable heavy and light chains of both antibodies were cloned and their sequences were determined. The VH of mAb 1A3-2 was found to express a germ line gene from the Q52 family, with a high homology to an anti-lysozyme antibody. The VH of monoclonal antibody 3F7-8 was found to express a 7183 germ line gene, showing over 95% homology with the VH of 12 anti-Sm antibodies isolated from MRL-lpr mice. Based on sequence homology to other known antibodies, we further demonstrated that monoclonal antibodies 1A3-2 and 3F7-8 bind lysozyme and the Sm ribonucleoproteins, respectively, in addition to their binding to the 16/6 Id.

Amelioration of experimental systemic lupus erythematosus (SLE) by retrovirus infection

Experimental SLE can be induced in susceptible 129/J mice by immunization with a human anti-DNA antibody bearing a common idiotype designated 16/6 Id. Immunized mice develop autoantibodies, leukopenia, proteinuria, and immune complex deposits in renal glomeruli. Case reports have described clinical improvement in SLE in individuals becoming infected with HIV-1. Because 129/J mice are susceptible to experimental SLE and to infection with the BM5def murine leukemia virus (MuLV) mixture but do not develop the lymphoproliferative/ immunodeficiency disorder known as murine AIDS (MAIDS), we superimposed this infection on immunization with the 16/6 Id. Multiple effects were observed. First, we noted an amelioration in the course of experimental SLE. Second, both in experimental SLE and in BM5def MuLV infection, immunoreactivity to HIV-1 gp120 was demonstrated, although gp120 is not present in the BM5def MuLV viruses. Third, production of autoantibodies characteristically found in SLE, e.g., anti-DNA, anti-RNP, and anti-SSA, was seen in BM5def MuLV-infected mice, demonstrating that an immune response as a consequence of infection had occurred despite the absence of MAIDS induction. We conclude that (1) retrovirus inoculation may ameliorate the course of experimental SLE; and (2) retrovirus inoculation, even in the absence of MAIDS induction, induces an immunologic response which promotes the production of potentially pathogenic autoantibodies.